Arylcarboxylic acid and pharmacologically acceptable salts thereof have been known to be extremely superior antiinflammatory agents. However, said arylcarboxylic acids, particularly pranoprofen, diclofenac and bromfenac, are associated with a problem that they become unstable in an aqueous solution.
Arylcarboxylic acid and pharmacologically acceptable salts thereof have been also known to be stabilized by adding an antioxidant, by adjusting the pH, concentration and ionic strength thereof, by shutting out the light, and the like. These methods, nevertheless, cannot provide sufficient stability at lower temperatures.
Thus, an aqueous solution has not been provided which contains an arylcarboxylic acid or a pharmacologically acceptable salt thereof, particularly pranoprofen, dicrofenac or bromfenac, and which has sufficient stability at lower temperatures.
While WO9632941A1 discloses pranoprofen combined with an organic amine, it does not disclose the heterocyclic base to be used in the present invention.